Pass Labs X0.2 still has issues....
nooshinjohn
Posts: 22,918
I have a new(to me) Pass Labs X1, that was just serviced and given a clean bill of health at the Lab just this past week. It was sent in because it had a loud and very audible "pop" between steps on the volume, and an audible "hiss" similar to what you would hear on a cassette tape back in the day. This hiss gets louder with each step up in volume and once an increment of 10 is achieved, the hiss steps back down again.
A large shift away from factory settings for DC offset were found and corrected, as well as a handful of capacitors found to be out of spec and replaced. The popping sound has been diminished by about 50 percent, but I find that the hissing noise is still there and very much a distraction to listening.
I sit 10 feet away from my speakers, and use Polk Audio SDA-SRS 1.2TL's, which have crossovers that have been recapped. The speakers are 91db sufficient. Driving them are my tube amplifiers. All connections to source components are made through XLR cables made by Audioquest.
My previous preamp was a Pass Labs X1, which exhibited none of the noise issues I have described. I do understand the pop sound is a function of the volume control and is a characteristic of it's design, and I am more than ok with that.
All functions of the pre work as intended and it sounds great otherwise. The only issue that really concerns me is that hissing sound. It is present regardless of source selected and can be heard some 20 feet away from the speaker even if nothing is playing. Is there something that can be done to reduce or eliminate this noise?
A large shift away from factory settings for DC offset were found and corrected, as well as a handful of capacitors found to be out of spec and replaced. The popping sound has been diminished by about 50 percent, but I find that the hissing noise is still there and very much a distraction to listening.
I sit 10 feet away from my speakers, and use Polk Audio SDA-SRS 1.2TL's, which have crossovers that have been recapped. The speakers are 91db sufficient. Driving them are my tube amplifiers. All connections to source components are made through XLR cables made by Audioquest.
My previous preamp was a Pass Labs X1, which exhibited none of the noise issues I have described. I do understand the pop sound is a function of the volume control and is a characteristic of it's design, and I am more than ok with that.
All functions of the pre work as intended and it sounds great otherwise. The only issue that really concerns me is that hissing sound. It is present regardless of source selected and can be heard some 20 feet away from the speaker even if nothing is playing. Is there something that can be done to reduce or eliminate this noise?
The Gear... Carver "Statement" Mono-blocks, TriangleArt Reference SE with Pass Labs Xono Phono Preamp, Walker Precision Motor Drive, ClearAudio Goldfinger Diamond v2 cartridge and Origin Conquerer Mk3c tonearm, Polk Audio "Signature" Reference Series 1.2TL with complete mods, Pass Labs X0.2 three chassis preamp, PS Audio PerfectWave DAC MkII, Krell Evolution 505 SACD Player, Pioneer Elite SC-LX701, Oppo UDP-205 4K Blu-ray player, Sony XBR70x850B 4k, Polk audio AB800 "in-wall" surrounds.
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
Comments
Belles 21A Pre modded with Mundorf Supreme caps
B&K M200 Sonata monoblocks refreshed and upgraded
Polk SDA 1C's modded
Wireworld Silver Eclipse IC's and speaker cables
Bummed
X1 and no noise at all. Swapping in the X0.2 and the noise is quite prevalent. All cables are the same. The only change was swapping the preamps. I have triple checked everything, swapped cables, disconnected the sda, everything I can think of. I think the troubles are within the volume control itself. I cannot fathom why they did not change it when it was there.
On the plus side.... holy crap this thing produces the largest soundstage I have ever heard come from my speakers. Everything was great before but now it is on an entirely different level. I hope a solution can be found, because I would hate to be on the prowl for a different preamp.
I am listening at low level right now and the nuance and micro detail is astonishing.
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
Lumin X1 file player
Sony XA-5400ES SACD
Pass XP-22 pre, X600.5 amps
Magico S5 MKII Mcast Rose speakers, SPOD spikes
Shunyata Triton v3/Typhon QR on preamp, Denali 2000 (2) on amps
Shunyata Sigma XLR analog ICs, Sigma speaker cables
Shunyata Sigma HC (2), Sigma Analog, Sigma Digital, Z Anaconda (3) power cables
Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
Three 20 amp circuits.
They say it takes 48 hours to warm up and settle in. Maybe I am being too hard on things right now, but something tells me this is just the character of this unit. I can't imagine Nelson Pass would accept this noise coming from a flagship preamp.
The detail this beast is capable of is astonishing. Bud... you had an XP30 before, correct? did you have a similar issue, or way it stone quiet? I might look to acquire an XP20 if I can't get this one sorted out.
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
Lumin X1 file player
Sony XA-5400ES SACD
Pass XP-22 pre, X600.5 amps
Magico S5 MKII Mcast Rose speakers, SPOD spikes
Shunyata Triton v3/Typhon QR on preamp, Denali 2000 (2) on amps
Shunyata Sigma XLR analog ICs, Sigma speaker cables
Shunyata Sigma HC (2), Sigma Analog, Sigma Digital, Z Anaconda (3) power cables
Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
Three 20 amp circuits.
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
Could it be some weird configuration issue or setting that has been overlooked? It does seem strange that Pass wouldn't give it a listening test before sending it back.
Belles 21A Pre modded with Mundorf Supreme caps
B&K M200 Sonata monoblocks refreshed and upgraded
Polk SDA 1C's modded
Wireworld Silver Eclipse IC's and speaker cables
Your not the only one. I have a hiss too in the upper frequencies after changing things back to what they were. Only thing that changed was the addition of a new older amp, same cables same everything same way everything was hooked up.
Had the amp looked at, it's fine. Changed tubes in the pre, fine, still there. Nothing is more aggravating in this hobby of ours than chasing down an errant sound that appears that wasn't there before. Nothing bothers me more, than an errant sound I can't locate from where it's coming from. So much so...that I'm ready to rip it all apart and start from scratch.
Sony 850c 4k
Pioneer elite vhx 21
Sony 4k BRP
SVS SB-2000
Polk Sig. 20's
Polk FX500 surrounds
Cables-
Acoustic zen Satori speaker cables
Acoustic zen Matrix 2 IC's
Wireworld eclipse 7 ic's
Audio metallurgy ga-o digital cable
Kitchen
Sonos zp90
Grant Fidelity tube dac
B&k 1420
lsi 9's
This can very much be the cause. Do you have the specs on the amp?
When I was speaking with Dan (Modwright) while pairing up a preamp with the Thresholds he asked for the specs. He tweaked the LS100 slightly to better match up the impedance pairing
https://forum.audiogon.com/discussions/how-to-match-preamp-and-power-amp
http://av2day.com/question/how-do-you-match-a-pre-amp-to-a-power-amp/
and many more on the web
Desktop rig: LSi7, Polk 110sub, Dayens Ampino amp, W4S DAC/pre, Sonos, JRiver
Gear on standby: Melody 101 tube pre, Unison Research Simply Italy Integrated
Gone to new homes: (Matt Polk's)Threshold Stasis SA12e monoblocks, Pass XA30.5 amp, Usher MD2 speakers, Dynaudio C4 platinum speakers, Modwright LS100 (voltz), Simaudio 780D DAC
erat interfectorem cesar et **** dictatorem dicere a
Sony 850c 4k
Pioneer elite vhx 21
Sony 4k BRP
SVS SB-2000
Polk Sig. 20's
Polk FX500 surrounds
Cables-
Acoustic zen Satori speaker cables
Acoustic zen Matrix 2 IC's
Wireworld eclipse 7 ic's
Audio metallurgy ga-o digital cable
Kitchen
Sonos zp90
Grant Fidelity tube dac
B&k 1420
lsi 9's
Not all gear plays well together and tube amps can be a bit more touchy.
John,
Knowing the caliber of the "lab", I am more inclined to think it's a gear mismatch more than a bad pre. Have you called and talked to Desmond or anyone else at Pass to bend their ear about your issue? You know how willing and helpful they can be. They would know more than anyone here what the issue might be.
It would be nice if someone close to test it on a SS amp just to see what shakes out.
Good luck and I'm sure you know Pass will bend over backwards to help you.
H9
Pass Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
Sony 850c 4k
Pioneer elite vhx 21
Sony 4k BRP
SVS SB-2000
Polk Sig. 20's
Polk FX500 surrounds
Cables-
Acoustic zen Satori speaker cables
Acoustic zen Matrix 2 IC's
Wireworld eclipse 7 ic's
Audio metallurgy ga-o digital cable
Kitchen
Sonos zp90
Grant Fidelity tube dac
B&k 1420
lsi 9's
input/output impedance need to match.
Preamp: deHavilland Ultraverve 3
Transport/Dac: L.K.S MH-DA004, Cayin Venus cd-100i, Musical Paradise mp-d2 mkI,
Musical Paradise mp-d2 mkIII
Speakers: Rosso Fiorentino Volterra II
Speaker Cables: Organic Audio Organic Reference 2, Analysis Plus Black Mesh Oval 9,
Cerious Technologies Graphene Extreme
Interconnects: Argento Organic Reference 2, Argento Organic 2, Gabriel Gold Reckoning
Power Cables by: Cullen Cables, 6sons Audio, Swiss Cables
https://electronics.stackexchange.com/questions/46948/the-10x-rule-for-impedance-bridging
The nominal input impedance of the amp and output impedance of the preamp should be available from their manufacturers' specifications.
FWIW. The most telling symptom, I think, is this (from the first post of the thread:
I am assuming that this preamp uses a resistive attenuator, which is not a constant impedance device. The maximum impedance of a resistive type volume control is, I have been told, maximum at an intermediate level of attenuation somewhere in the middle of its adjustment range, and it is not uncommon for a component (preamp, integrated amp, or receiver) to display a maximum level of hum at an intermediate setting of the "volume control".
Now, hum is not hiss*, and perhaps the attenuator in the component in question is a constant impedance network rather than simply adjustable resistance, but I am guessing that the symptom arises from an impedance issue of some sort.
Just a cluster of SWAGs, though.
______________
* FWIW: "hiss", in my experience, is usually thermionic noise (tubes) or "shot noise" (transistors), and is also usually most audible at minimum attenuation ("high volume" settings).
2 Hz to 85 kHz (–3 dB)
Distortion: Less than 0.5%
Power Bandwidth: 24 Hz to 28 kHz without filters
Line Inputs: 1RCA
Input Impedance: 100 K ohms (RCA)
Gain: 30 dB (8 ohms)
Tube Complement: One 12AX7, one 12AT7, one 6AL5, six KT120
Hum and Noise: Better than 120 dB, referred to 350 watts, A-weighted
Preamp specs for the X0.2
Gain 14dB or 20dB
Gain adjustment Internal
Number of volume control steps 72
Freq. Response -3dB @ 2Hz, -3dB @ 100kHz
Distortion @ 1KHz <0.1% THD typ, 0.003% @ 2V
Output Voltage 20 Balanced, 7 Single-ended
Output Impedance 750 Balanced, 150 Single-ended
Input Impedance 20K Balanced, 10K Single-ended
Number of gain paths 4
Separate analog channels Yes
Remote control Yes
Input voltage before overload 11
CMRR 80db 20-20kHz
Output noise floor -110dBV ref to 20V output
Crosstalk typ. -90dB 20 - 20kHz
External amp turn on
Single-ended only inputs 5
Balanced / single ended inputs 6
Mono operation setting Yes
Unity gain setting Yes
Power Supply External
Power consumption 30 watts
Number of chassis Dimensions 3
Weight 72
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
preamp output impedance: 150 ohm (unbalanced), 750 ohm (balanced)
Certainly no mismatch between the two for an unbalanced connection.
Are you running balanced or unbalanced?
___________
* Presumably also high -- does the amp have balance inputs?
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
If your read closely between the lines in the owner's manuals of most, if not all, X gear, it's suggested to run balanced for best results and performance.
Just throwing that out there.
H9
Pass Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!
If I were @nooshinjohn, I'd try a different set of cables 'twixt preamp and power amplifier. Couldn't hoit
Oh, I assume it does this independent of source input, yes? In other words, if (for example) the preamp has no inputs at all connected, it will still manifest the hiss at some intermediate attenuation (volume) levels, yes?
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
Digital: I3 pc w/ Jriver playing flac -> Sonore Ultrarendu -> Twisted Pair Audio ESS 9028 w/ Mercury IVY
Vinyl rips-> ESI [email protected]/192->fanless i3 pc server
Yes, it does this independent of source selected and is still present even with no source connected to the preamp. The hiss is present even if the attenuation is set to zero. It is also present in both left and right channels, with or without the SDA connection. In my mind, that eliminates cables or source components from being an issue.
It would appear to be exclusive to the preamp itself, or in the match between amps and preamp.
I swear by my life and my love of it that I will never live for the sake of another man, nor ask another man to live for mine.” .
“If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
Might want to have a look see over there
H9
Pass Aleph 30 | EE Avant Pre | EE Mini Max Plus DAC | MIT Shotgun S3 | MIT Z P/C's | updated SDA 1C| SQ Box Touch/Welbourne Labs P/S- Tubes add soul!